Free software license

free software licencefree softwarefree software licensesfreefree software licencesFree-software licenseFree Software licensingfree-software licenseslicensesfree and open-source software license
A free-software license is a notice that grants the recipient of a piece of software extensive rights to modify and redistribute that software.wikipedia
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Apache License

Apache License 2.0Apache 2.0Apache
In 2015 according to Black Duck Software and GitHub statistics, the permissive MIT license dethroned the GPLv2 as most popular free-software license to the second place while the permissive Apache license follows already at third place.
The Apache License is a permissive free software license written by the Apache Software Foundation (ASF).

Proprietary software

ProprietaryClosed sourceclosed-source
As a result, BSD code can be used in proprietary software that only acknowledges the authors.
Occasionally, software is made available with fewer restrictions on licensing or source-code access; such software is known as "free" or "open-source."

Comparison of free and open-source software licenses

List of software licensesfree software licensesComparison of free software licenses
In this trend companies and new projects (Mozilla, Apache foundation, and Sun, see also this list) wrote their own FOSS licenses, or adapted existing licenses.
FSF's free software and OSI's open-source licenses together are called FOSS licenses.

GNU Lesser General Public License

LGPLGNU LGPLLGPLv2.1
In June 2016 an analysis of Fedora Project's packages revealed as most used licenses the GPL, MIT, BSD, and the LGPL.
The GNU Lesser General Public License (LGPL) is a free-software license published by the Free Software Foundation (FSF).

Software

Computer softwareSoftware & Programmingsoftware technology
Free-software licenses are applied to software in source code and also binary object-code form, as the copyright law recognizes both forms.
The software's license gives the user the right to use the software in the licensed environment, and in the case of free software licenses, also grants other rights such as the right to make copies.

Public-domain software

public domain softwarepublic domainPublic-domain
Therefore, software had no licenses attached and was shared as public-domain software.
To refer to free software (which is under a free software license) or to software distributed and usable free of charge (freeware) as "public-domain" is therefore incorrect.

Aladdin Free Public License

AFPLAFP license
Despite the name, the Free Software Foundation does not consider the AFPL a free software license, neither the OSI consider it an open-source license, nor does it fall under the Copyfree Standard definition.

Open-source software

open sourceopen-sourceopen source software
Starting in the mid-1990s and until the mid-2000s, the open-source movement pushed and focused the free-software idea forward in the wider public and business perception.
Examples of free software license / open-source licenses include Apache License, BSD license, GNU General Public License, GNU Lesser General Public License, MIT License, Eclipse Public License and Mozilla Public License.

WTFPL

Do What The Fuck You Want To Public LicenseWTFPLv2
Examples of public-domain-like licenses are, for instance, the WTFPL and the CC0 license.
WTFPL is a GPL-compatible permissive license most commonly used as a free software license.

GNU General Public License

GPLGNU GPLGPLv2
In 1989, version1 of the GNU General Public License (GPL) was published. This has very little impact however since the Artistic License is almost always used in a dual-license setup, along with the GNU General Public License.
The GNU General Public License (GNU GPL or GPL) is a widely-used free software license that guarantees end users the freedom to run, study, share, and modify the software.

MIT License

MITX11 LicenseMIT Licence
In 2015 according to Black Duck Software and GitHub statistics, the permissive MIT license dethroned the GPLv2 as most popular free-software license to the second place while the permissive Apache license follows already at third place.
, according to Black Duck Software and a 2015 blog from GitHub, the MIT license was the most popular free software license, with the GNU GPLv2 coming second in their sample of repositories.

GNU Project

GNUFSDGGNU Free System Distribution Guidelines
In the mid-1980s, the GNU project produced copyleft free-software licenses for each of its software packages.

Apple Public Source License

APSLApple Public SourceAPSL 2.0
As an example, the Apple Public Source License may terminate a user's rights if said user embarks on litigation proceedings against them due to patent litigation. Examples of licenses that provoked debate were the 1.x series of the Apple Public Source License, which were accepted by the Open Source Initiative but not by the Free Software Foundation or Debian and the RealNetworks Public Source License, which was accepted by Open Source Initiative and Free Software Foundation but not by Debian.
The Apple Public Source License (APSL) is the open-source and free software license under which Apple's Darwin operating system was released.

Software patents and free software

Patent retaliationsoftware patents
During the 1990s, free-software licenses began including clauses, such as patent retaliation, in order to protect against software patent litigation cases – a problem which had not previously existed.
"Patent retaliation" clauses are included in several free software licenses.

Google Developers

Google CodeGoogle APIGoogle Web API
On the other hand, in 2009, two years after the release of the GPLv3, Google open-source programs office manager Chris DiBona reported that the number of open-source projects licensed software that had moved to GPLv3 from GPLv2 was 50%, counting the projects hosted at Google Code.
The service was available and free for all OSI-approved Open Source projects (as of 2010, it was strongly recommended but no longer required to use one of the nine well-known open source licenses: Apache, Artistic, BSD, GPLv2, GPLv3, LGPL, MIT, MPL and EPL).

Debian Free Software Guidelines

DFSGDebian's guidelinesDFSG free
The Debian project uses the criteria laid out in its Debian Free Software Guidelines (DFSG).
The Debian Free Software Guidelines (DFSG) is a set of guidelines that the Debian Project uses to determine whether a software license is a free software license, which in turn is used to determine whether a piece of software can be included in Debian.

Free and open-source software

free and open-sourcefree and open source softwareFOSS
Software using such a license is free software (or free and open-source software) as conferred by the copyright holder.
That is, anyone is freely licensed to use, copy, study, and change the software in any way, and the source code is openly shared so that people are encouraged to voluntarily improve the design of the software.

Attribution (copyright)

attributionattributedattribution of authorship
Permissive licenses might carry small obligations like attribution of the author but allow practically all code use cases.
Author attribution is required by several licenses, such as the open-content Creative Commons licenses and most free and/or open source software licenses such as the MIT permissive license.

Multi-licensing

dual-licenseddual-licensingdual license
This has very little impact however since the Artistic License is almost always used in a dual-license setup, along with the GNU General Public License.
In this scenario, one option is a proprietary software license, which allows the possibility of creating proprietary applications derived from it, while the other license is a copyleft free software/open-source license, thus requiring any derived work to be released under the same license.

Artistic License

ArtisticArtistic License 2.0Artistic 2.0
The only notable cases where Debian and Free Software Foundation disagree are over the Artistic License and the GNU Free Documentation License (GFDL).
Whether or not the original Artistic License is a free software license is largely unsettled.

Open-source license

open sourceopen-sourceopen source license
In 2012 the dispute was finally resolved when Rosen accepted the CC0 as open source license, while admitting that contrary to his previous claims copyright can be waived away, backed by Ninth circuit decisions.

Copyleft

copyleft licenseweak copyleftSoftware hoarding
In the mid-1980s, the GNU project produced copyleft free-software licenses for each of its software packages.
Many free-software licenses are not copyleft licenses because they do not require the licensee to distribute derivative works under the same license.

RealNetworks Public Source License

RPSL
Examples of licenses that provoked debate were the 1.x series of the Apple Public Source License, which were accepted by the Open Source Initiative but not by the Free Software Foundation or Debian and the RealNetworks Public Source License, which was accepted by Open Source Initiative and Free Software Foundation but not by Debian.
It has been approved as a free software licence by both Free Software Foundation and Open Source Initiative (OSI), but it is incompatible with the GPL and the Debian Free Software Guidelines.

Software patent

software patentspatentpatents
During the 1990s, free-software licenses began including clauses, such as patent retaliation, in order to protect against software patent litigation cases – a problem which had not previously existed.
Much of this has been caused by free software or open source projects terminating when the owners of patents covering aspects of a project demanded license fees that the project could not pay, or was not willing to pay, or offered licenses with terms that the project was unwilling to accept, or could not accept, because it conflicted with the free software license in use.

BSD licenses

BSD licenseBSDNew BSD License
The original BSD license is also one of the first free-software licenses, dating to 1988.
Two variants of the license, the New BSD License/Modified BSD License (3-clause), and the Simplified BSD License/FreeBSD License (2-clause) have been verified as GPL-compatible free software licenses by the Free Software Foundation, and have been vetted as open source licenses by the Open Source Initiative.